1. Field of the Invention
The present invention relates generally to an apparatus for controlling an illumination device, and more particularly, to an apparatus for controlling an illumination device capable of performing optical communication.
2. Description of the Related Art
Extensive research has recently been conducted on the use of a light emitting element in illumination devices. Due to the increase in the luminary power of a light emitting element, such as a Light Emitting Diode (LED), it has become possible to realize an illumination device by using such a light emitting element. Furthermore, next-generation illumination devices are being targeted for extensive use of light emitting elements, due to their inherent long life, high efficiency, and high-speed response properties.
A light emitting element-using illumination device requires a relatively high optical power, and thus generally has a configuration in which a plurality of light emitting elements such as white LEDs are mounted in a circuit board to constitute one module.
FIG. 1 illustrates a conventional light emitting element-using illumination device. Referring to FIG. 1, the conventional light emitting element-using illumination device includes an optical array 10 provided with a plurality of light emitting elements such as LEDs 11, 12, 13, 14, and 15, and an optical array driving unit 20 for controlling the driving of the optical array 10. The optical array driving unit 20 controls the driving of the optical array 10 by using a control signal based on Pulse Width Modulation (PWM) in order to reduce the heat-generation and power-consumption of the light emitting element.
For example, the optical array driving unit 20 outputs a PWM control signal to the optical array 10 in consideration of an illumination device user's required brightness and the user's recognizable lighting frequency. Also, the optical array 10 lights the light emitting elements 11, 12, 13, 14, and 15 in unison, to generate an illumination light with a user's required brightness.
Meanwhile, as portable wireless devices are becoming even more widely used, these devices have incorporated the use of a wireless signal, such as infrared rays or radio waves. However, the use of such wireless communication devices is compromised due to depletion of radio wave resources, and the influence on a human body (e.g., eyes) and a medical device. Accordingly, there has been developed a wireless visible ray communication using a visible ray that is a safer transmission medium for communication compared to a conventional medium. Furthermore, research has been conducted on developing technology for applying the wireless visible ray communication to the above described light emitting element-using illumination device.
However, the above described light emitting element-using illumination device is generally configured such that the light emitting elements 11, 12, 13, 14, and 15 provided within the optical array 10 can be lit at one time, by using a PWM control signal. Accordingly, when the wireless visible ray communication is applied to the illumination device, the communication ends in the interval where the light emitting elements 11, 12, 13, 14, and 15 are off, causing a reduction in communication efficiency. In addition, a communication signal is inefficiently modulated in consideration of the timing of the interval where the light emitting elements 11, 12, 13, 14, and 15 are off.